Light emitting device

ABSTRACT

A light emitting device includes: a base having a first stepped portion and a second stepped portion; a light emitting element; an electronic member configured to be irradiated by light emitted from the light emitting element; a first wiring region located on the first stepped portion; a second wiring region located on the second stepped portion; wires connected to the light emitting element and the electronic member. The wires includes a first and second wires. The first wire has a first end that is connected to the first wiring region, and a second end. The second wire has a first end that is connected to the second wiring region, and a second end. A position of the second end of the first wire relative to the bottom face is lower than a position of the second end of the second wire relative to the bottom face.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2019-220036, filed on Dec. 5, 2019, the disclosure of which is herebyincorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a light emitting device.

As disclosed in Japanese Patent Publication No. 2014-157873, an opticalmodule having a stepped portion in a recessed base and bonding wiresconnected to the stepped portion is known. Furthermore, in the opticalmodule disclosed in this patent publication, a light receiving elementin addition to a light emitting element is disposed in the recessedportion.

SUMMARY

A light emitting device according to the certain embodiments includes abase, a light emitting element, an electronic member, a first wiringregion, a second wiring region, a plurality of wires. The base has abottom face and a lateral part surrounding the bottom face and extendingupwards from the bottom face. The lateral part includes a first steppedportion and a second stepped portion that are each defined by an innerlateral face and an upper face. A height of the second stepped portionfrom the bottom face is greater than a height of the first steppedportion from the bottom face. The light emitting element is disposed onthe bottom face. The electronic member is disposed on the bottom faceand configured to be irradiated by light emitted from the light emittingelement. The first wiring region is located on the first steppedportion. The second wiring region is located on the second steppedportion. The plurality of wires are connected to the light emittingelement and the electronic member. The plurality of wires include afirst wire and a second wire. The first wire has a first end that isconnected to the first wiring region, and a second end. The second wirehas a first end that is connected to the second wiring region, and asecond end. A position of the second end of the first wire relative tothe bottom face, is lower than a position of the second end of thesecond wire relative to the bottom face.

According to the present disclosure, in a light emitting deviceincluding a light emitting element and an electronic member, the wirebonding of the light emitting element and the electronic member can befacilitated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a light emitting device according to afirst embodiment.

FIG. 2 is a perspective view of the light emitting device according tothe first embodiment from which the cover member is removed.

FIG. 3 is a top view of the light emitting device according to the firstembodiment from which the cover member is removed.

FIG. 4 is a cross-sectional view of the light emitting device takenalong line IV-IV in FIG. 3.

FIG. 5 is a perspective view of a light emitting device according to asecond embodiment.

FIG. 6 is a perspective view of the light emitting device according tothe second embodiment from which the cover member is removed.

FIG. 7 is a top view of the light emitting device according to thesecond embodiment from which the cover member is removed.

FIG. 8 is a cross-sectional view of the light emitting device takenalong line VIII-VIII in FIG.

FIG. 9 is a top view of an electronic member according to the secondembodiment.

FIG. 10 is a perspective view of a light emitting device according to athird embodiment.

FIG. 11 is a top view of the light emitting device according to thethird embodiment from which the cover is removed.

DETAILED DESCRIPTION

In the description and the accompanying claims, a polygon, such as atriangle, rectangle, or the like, including a shape subjected toprocessing, such as cutting angles, beveling, chamfering, rounding, orthe like, will be referred to as a polygon. Moreover, the location ofsuch processing is not limited to a corner (an end of a side). Rather, ashape subjected to processing in the middle of a side will similarly bereferred to as a polygon. In other words, any polygon-based shapesubjected to processing should be understood to be included in theinterpretation of a “polygon” in the description and accompanyingclaims.

This similarly applies to any word describing a specific shape, such asa trapezoidal, circular, recessed, or projected shape, without beinglimited to a polygon. This also similarly applies to the sides definingsuch shapes. In other words, even if a corner or middle of a side issubjected to processing, the term “side” should be interpreted toinclude the processed portion. To distinguish a “polygon” or “side” thatis intentionally not processed from a shape subjected to processing, theshape will be described by adding the phrase “exact,” such as “an exactrectangle.”

Moreover, in the description and accompanying claims, in the case inwhich there are a plurality of pieces of a certain constituent elementand a distinction must be made, a word such as “first,” “second,” or thelike might occasionally be added. The manner in which such a word isused in the description might not match the manner in which such a wordis used in the claims if the subject to be distinguished or theperspective for such a distinction differs.

For example, in the case in which there are a plurality of an elementdenoted and distinguished by “first,” “second,” and “third” in thedescription, and a certain claim recites only those that are referred toas the “first” and “third” in the description, what are referred to asthe “first” and “second” in the claim might correspond to what arereferred to as the “first” and “third” in the description.

Certain embodiments of the present invention will be explained belowwith reference to the accompanying drawings. The embodiments describedbelow are provided to give shape to the technical ideas of the presentinvention, and are not intended to limit the present invention. In theexplanation below, the same designations and reference numerals denotethe same or similar members, and redundant explanations will be omittedas appropriate. The sizes and relative positions of the members shown inthe drawings might be exaggerated for clarity of explanation.

First Embodiment

A light emitting device 1 according to a first embodiment will beexplained. FIG. 1 to FIG. 4 are drawings illustrating a light emittingdevice 1. FIG. 1 is a perspective view of the light emitting device 1.FIG. 2 is a perspective view of the light emitting device 1 in the statein which the cover member 80 is not shown. FIG. 3 is a top view in thesame state as in FIG. 2. FIG. 4 is a cross-sectional view taken alongline IV-IV in FIG. 3.

The light emitting device 1 has a plurality of constituent elementsincluding a base 10, three semiconductor laser elements 20, a submount30, an electronic member 40, a support member 50, an optical member 60,a plurality of wires 70, and a cover member 80 (see FIG. 4, inparticular, for the support member 50).

In the light emitting device 1, the three semiconductor laser elements20, the submount 30, the electronic member 40, the support member 50,the optical member 60, and the wires 70 are arranged in the spacesurrounded by the base 10 and the cover member 80. In the light emittingdevice 1, light is emitted by the three semiconductor laser elements 20disposed in the space. Each constituent element will be explained first.

Base 10

The base 10 has an arrangement region in which other constituentelement(s) are arranged, and lateral walls that surround the arrangementregion. The base 10 has a recessed portion, which includes thearrangement region and the lateral walls. The recessed portion isdepressed in the direction from the upper face to the lower face of thebase 10. In the present disclosure, the bottom of the recessed portionwill be referred to as the bottom face of the base 10. The bottom faceof the base 10 can be a main portion of the arrangement region.

The periphery of the base 10 is rectangular in a top view. The peripheryof the recessed portion is rectangular in the top view. Furthermore, inthe top view, the rectangular periphery of the bottom face of the base10 is smaller than the periphery of the recessed portion. It is notessential for any of these to have a rectangular periphery.

The base 10 has a bottom part 11 and lateral parts 12. The bottom part11 comprises the bottom face of the base 10. The bottom part 11 includesthe bottom face and the lower face of the base 10. The lateral part 12comprises the lateral walls of the base 10. Accordingly, the lateralpart 12 surrounds the bottom face of the base 10 as well as upwardlyextending from the bottom face. Moreover, the lateral part 12 includesone or more outer lateral faces, one or more inner lateral faces, and anupper face meeting the outer lateral face(s) and the inner lateralface(s).

The number of inner lateral faces or the outer lateral faces depends onthe shape surrounding the bottom face. For example, in the case in whichthe shape surrounding the bottom face is rectangular, inner lateralfaces are formed to correspond to the four sides of the rectangle; i.e.,there are a plurality of inner lateral faces. In the case in which theshape surrounding the bottom face is circular, one inner lateral face isformed to correspond to a circle; i.e., there is a single inner lateralface. The same is true for the outer lateral faces.

The base 10 has a plurality of stepped portions. A stepped portion isspecified here as a portion composed only of an upper face and an innerlateral face(s) meeting the upper face and extending downwardstherefrom. The stepped portions are included as parts of the lateralpart 12 of the base 10. Each of the stepped portions is provided betweenthe bottom face and the upper face of the base 10. In the top view,moreover, each stepped portion is formed between the periphery of therecessed portion and the periphery of the bottom face of the base 10.

Each of the stepped portions is formed along the inner lateral face ofthe base 10 which meet the upper face of the base 10. Accordingly, theupper face of each stepped portion meets the inner lateral face of thebase 10 which meets the upper face of the base 10. The steps formed bythe stepped portions extend along the entire perimeter of one or more ofthe inner lateral faces that surround the arrangement region of the base10. However, the steps formed by the stepped portions do not have to beformed along the entire perimeter.

The stepped portions include a first stepped portion 13 and a secondstepped portion 15. In the light emitting device 1 illustrated in thedrawings, the stepped portions are configured as only of the firststepped portion 13 and the second stepped portion 15, but can have oneor more additional stepped portions.

The first stepped portion 13 and the second stepped portion 15 havedifferent heights. In other words, the heights of the upper faces of thefirst stepped portion 13 and the second stepped portion 15 from thebottom face of the base 10 differ. In the case of the light emittingdevice 1 shown in the drawings, the second stepped portion 15 ispositioned higher from the bottom face than the first stepped portion13. The base can have a first stepped portion 13 which is positionedhigher than a second stepped portion 15.

The first stepped portion 13 and the second stepped portion 15 are eachformed along a portion of the inner lateral faces of the base 10 thatmeets the upper face of the base. Accordingly, the upper face of thefirst stepped portion 13 meets certain portions of the inner lateralfaces of the base 10 that meet the upper face of the base, and the upperface of the second stepped portion 15 meets certain portions of theinner lateral faces of the base 10 that meet portions of the upper faceof the base 10 that are different from those met by the upper face ofthe first stepped portion 13.

In the top view, the total length of one or more of the inner lateralfaces of the base 10 meeting the upper face thereof along which thefirst stepped portion 13 is formed is larger than the total length ofthe inner lateral faces along which the second stepped portion 15 isformed. Moreover, the second stepped portion 15 is formed along aportion of the overall perimeter of the one or more inner lateral faces,and the first stepped portion 13 is formed along the remaining portionof the overall perimeter.

In the light emitting device 1 illustrated in the drawings, which has arectangular periphery defined by four inner lateral faces in the topview, the total length of the portions along which the first steppedportion 13 is formed is equal to or larger than the sum of the lengthsof the two long sides of the rectangle, but equal to or less than thesum of the two long sides and one short side of the rectangle. Thelength of the portion along which the second stepped portion 15 isformed is equal to or larger than the length of one short side of therectangle, but equal to or less than the length of one long side of therectangle.

One or more of the inner lateral faces of the first stepped portion 13have lower sides that meet the bottom face of the base 10. The innerlateral face of the second stepped portion 15 has lower side(s) thatmeets the base 10. Because the stepped portions are formed so as to risefrom the bottom face, the stepped portions can be provided in thepositions near the arrangement region. The total length of the portionswhere the first stepped portion 13 meets the bottom face of the base 10is larger than the length of the portion where the second steppedportion 15 meets the bottom face of the base 10.

The lower sides of the inner lateral faces of the first stepped portion13 do not meet the second stepped portion 15 except for the endpoints ofthe sides. At the endpoints, the inner lateral face of the secondstepped portion 15 meets the bottom face of the base 10.

The inner lateral face of the second stepped portion 15 has a lower sidemeeting the bottom face of the base 10 and a lower side meeting theupper face of the first stepped portion 13. The length of the portionwhere the inner lateral face of the second stepped portion 15 meets thebottom face of the base 10 is larger than the length of the portionswhere the inner lateral face of the second stepped portion 15 meets theupper face of the first stepped portion 13. In this manner, a largebottom face as well as an adequate arrangement region can be secured.

The height of the second stepped portion 15 from the bottom face of thebase 10 is preferably in the range of from 1.2 to 3.0 times the heightof the first stepped portion 13 from the bottom face of the base 10. Itis preferable for the height of the first stepped portion 13 to besmaller than one half of the height from the bottom face to the upperface of the base 10, and the height of the second stepped portion 15 tobe larger than the height from the bottom face to the upper face of thebase 10.

One or more first wiring regions 14 are provided on the upper face ofthe first stepped portion 13. In the light emitting device 1 illustratedin the drawings, a plurality of first wiring regions 14 are provided.The first wiring regions 14 are electrically connected through theinterior of the base 10 to the wiring regions provided on the lower faceof the base 10. The wiring regions to be electrically connected to thefirst wiring regions 14 can be provided on the outer surfaces (upperface, outer lateral faces, and/or lower face) of the base 10, withoutlimiting the location to the lower face of the base 10.

One or more second wiring regions 16 are provided on the upper face ofthe second stepped portion 15. In the light emitting device 1illustrated in the drawings, a plurality of second wiring regions 16 areprovided. The second wiring regions 16 are electrically connectedthrough the interior of the base 10 to the wiring regions disposed onthe lower face of the base 10. The wiring regions to be electricallyconnected to the second wiring regions 16 can be provided on the outersurfaces (upper face, outer lateral faces, and/or lower face) of thebase 10, without limiting the location to the lower face of the base 10.

The base 10 can be formed using a ceramic as a main material. Examplesof ceramics for use as the base 10 include aluminum nitride, siliconnitride, aluminum oxide, silicon carbide, and the like.

The base 10 can be formed in such a way that the bottom part 11 and thelateral part 12 are monolithic. Alternatively, the base can be formed ina manner that the bottom part 11 and the lateral part 12 are formedusing different main materials and are joined. In this case, a metal canbe used as a main material for the base portion 11, and a ceramic as amain material for the lateral part 12.

In this case, furthermore, the metal employed for the bottom part 11 ispreferably one having good heat dissipation properties (higher thermalconductivity) than the ceramic employed for the lateral part 12. Forexample, copper, aluminum, iron, as well as a composite material, suchas copper-molybdenum, copper-diamond, copper-tungsten, or the like, canbe used.

A metal film is disposed in the locations in the base 10 that correspondto the first wiring regions 14, the wiring regions to be electricallyconnected thereto, the second wiring regions 16, and the wiring regionsto be electrically connected thereto. A metal material is also disposedat the locations in the interior of the base for electrical connection,which achieves the electrical connection.

Semiconductor Laser Element 20

A semiconductor laser element 20 has a rectangular periphery in the topview. The lateral face meeting one of the two short sides of therectangle serves as the emission face through which the light exits fromthe semiconductor laser element 20. The upper face and the lower face ofthe semiconductor laser element 20 have larger areas than the emissionface.

Moreover, a semiconductor laser element 20 is a multi-emitter having twoemitters. An electrode shared by the two emitters is provided on one ofthe upper and lower faces of the semiconductor laser element 20, and twoelectrodes corresponding to the emitters are provided on the other face.

The light (laser beam) emitted from each emitter of a semiconductorlaser element 20 spreads, forming an elliptical far field pattern(hereinafter referred to as “FFP”) in a plane parallel to the emissionface. FFP represents the shape and light intensity distribution of theemitted light at a location distant from the emission face.

In the present disclosure, the light passing through the center of anelliptical FFP, i.e., the light having the peak intensity in the FFPlight intensity distribution, will be referred to as the light advancingalong the optical axis. The light having an intensity of at least 1/e²relative to the peak intensity value based on the light intensitydistribution of an FFP will be referred to as the main portion of theemitted light.

The shape of the FFP of the emitted light from a semiconductor laserelement 20 is an ellipse that is longer in the stacking direction of thesemiconductor layers including the active layer than in the layerdirection perpendicular to the stacking direction of the semiconductorlayers. The layer direction will be referred to as the lateral directionof the FFP, and the stacking direction will be referred to as thevertical direction of the FFP.

Based on an FFP light intensity distribution, the angle corresponding tothe full width at half maximum of the light intensity distribution willbe referred to as the divergence angle of light emitted form asemiconductor laser element. The divergence angle in the verticaldirection of an FFP will be referred to as vertical divergence angle,and the divergence angle in the horizontal direction of an FFP will bereferred to as horizontal divergence angle.

For a semiconductor laser element 20, for example, a blue light emittingsemiconductor laser element, a green light emitting semiconductor laserelement, or a red light emitting laser element can be employed. Asemiconductor laser element emitting light of a color other than thesecan be employed.

In the present disclosure, blue light refers to light having a peakemission wavelength in the 420 nm to 494 nm range, green light refers tolight having a peak emission wavelength in the 495 nm to 570 nm range,and red light refers to light having a peak emission wavelength in the605 nm to 750 nm range.

Examples of blue or green light emitting semiconductor laser elementsinclude semiconductor laser elements including nitride semiconductors.Examples of usable nitride semiconductors include GaN, InGaN, and AlGaN.Examples of usable red light emitting semiconductor laser elementsinclude those that include InAlGaP-based, GaInP-based, GaAs-based, andAlGaAs-based semiconductors.

Submount 30

A submount 30 is shaped as a rectangular cuboid having two opposingbonding faces. The distance between the two opposing bonding faces issmaller than the distance between the other two opposing faces. Theshape of the submount 30 is not limited to a rectangular cuboid. Thesubmount 30 can be formed with, for example, silicon nitride, aluminumnitride, or silicon carbide. A metal film is formed on the upper face ofthe submount 30.

Electronic Member 40

An electronic member 40 has a bonding face and a light-irradiated face.The bonding face and the light-irradiated face oppose to each other. Theelectronic member 40 is a part of the optical control unit that controlsthe light being irradiated on the light-irradiated face.

For an electronic member 40, for example, a microelectromechanicalsystem (hereinafter referred to by using the acronym, MEMS) can beemployed. Alternatively, for example, a light receiving element such asa photodiode (hereinafter referred to by using the acronym, PD) can beused. The electronic member 40 can reflect at least 80% of the lightirradiated on the light-irradiated face.

Support Member 50

A support member 50 has a lower face, and an oblique face 51 that isoblique to the lower face. The oblique face 51 is not perpendicular orparallel to the lower face. For example, the oblique face 51 is formedas a plane forming an inclination angle of 45 degrees to the lower face.The inclination angle is not limited to 45 degrees. Furthermore, thesupport member 50 includes only the oblique face 51 or one or moreadditional oblique faces each oblique to the lower face of the supportmember 50. In the case in which the support member 50 includes theoblique face 51 and the one or more oblique faces, the oblique face 51is one having the largest area.

Furthermore, the oblique face 51 occupies at least 60% of the area ofthe support member 50 in the top view. Furthermore, in the top view, thewidth from the upper edge to the lower edge of the oblique face 51 is atleast 60% of the width of the support member 50 in the same direction.In other words, the support member 50 has the structure in which theoblique face 51 accounts for a major percentage in this direction.

The support member 50 can be formed of, for example, ceramics, glass, ormetals. For example, ceramics such as aluminum nitride, glass such asquartz or borosilicate glass, and metals such as aluminum can be used.Alternatively, the support member can be formed by using Si or the like.

Optical Member 60

An optical member 60 has a bonding face and a lens face 61. The lensface 61 includes a lens shaped face. The optical member is oriented suchthat the lens face 61 becomes a lateral face in the case in which thebonding face is the lower face.

The lens face 61 has a shape in which a plurality of lenses areconnected in a row. In the present embodiment, the lens face 61 isformed by connecting three lenses in a lateral side view. The opticalmember 60 can be formed by using glass, for example, BK7 glass.

Wire 70

A wire 70 has a linear shape with both ends as bonding portions. Inother words, the wire has bonding portions at both ends of the linearportion to be bonded to other constituent elements. A wire 70 is, forexample, a metal wire. For example, gold, aluminum, silver, copper, orthe like can be used.

Cover Member 80

A cover member 80 is a plate-shaped rectangular cuboid having a lowerface and an upper face. The shape does not have to be a rectangularcuboid. Furthermore, the cover member 80 has light transmissivity.Accordingly, the cover member 80 can also be referred to as a lighttransmissive member. A light transmissive member without having a roleas a cover can be used.

In the present application, transmissivity is defined as having lighttransmissivity of at least 80%. It does not have to have transmissivityof at least to 80% for light of all wavelengths. The cover member 80 canhave a non-transmissive region (the region having no or less lighttransmissivity) in one portion.

The cover member 80 can be formed of sapphire. Sapphire is a materialhaving light transmissivity, a relatively high refractive index, andrelatively high strength. Besides sapphire, glass, for example, can beused.

Light Emitting Device 1

A light emitting device 1 will be explained next. The light emittingdevice 1 includes a base 10, three semiconductor laser elements 20disposed on the base 10, an electronic member 40 disposed on the base10, and wires 70. The wires 70 includes a plurality of first wires 71for electrically connecting the three semiconductor laser elements 20,and a plurality of second wires 72 for electrically connecting theelectronic member 40.

In the light emitting device 1, the three semiconductor laser elements20 are disposed on the base 10 via a submount 30. The semiconductorlaser elements 20 can be disposed directly on the bottom face of thebase 10 without interposing a submount 30. In this case, the outer shapeof each semiconductor laser element 20 may be changed in order to adjustthe light emitting position (height) of the emission face.

The electronic member 40 is disposed on the base 10 via a support member50. It can be directly disposed on the bottom face of the base 10without interposing a support member 50. In this case, the shape of theelectronic member 40 may be changed in order to adjust the position(height) and the direction (inclination) of the light-irradiated face41.

Furthermore, the light emitting device 1 includes an optical member 60disposed on the base 10. Moreover, the light emitting device 1 includesa cover member 80 which is joined to the base 10 and seals the space inwhich the three semiconductor laser elements 20 are disposed.

The three semiconductor laser elements 20 are disposed on the bottomface of the base 10. Accordingly, it can be said that they are disposedon the bottom part 11 of the base 10. The three semiconductor laserelements 20 are arranged in a row such that their emission faces facethe same direction. The lateral faces meeting the emission faces faceone another between adjacent semiconductor laser elements 20.

The three semiconductor laser elements 20 can be composed of, forexample, a blue light emitting semiconductor laser element, a greenlight emitting semiconductor laser element, and a red light emittingsemiconductor laser element. They can be composed of multiplesemiconductor laser elements emitting light of the same color, orinclude a semiconductor laser element emitting light of another color.

The number of semiconductor laser elements 20 disposed in a lightemitting device 1 does not have to be three. The number can be more thanthree or less than three. Instead of the semiconductor laser elements20, other light emitting elements such as LEDs can be used. The lightemitting device 1 has at least one light emitting element.

The submount 30 is bonded to the semiconductor laser elements 20 usingone bonding face, and is bonded to the bottom face of the base 10 usingthe other bonding face. Accordingly, it can be said that the submount isdisposed on the bottom part 11 of the base 10.

The light emitting device 1 can have a plurality of submounts 30. Inthis case, the number of semiconductor laser elements 20 bonded to onesubmount 30 does not have to be three, i.e., it can be two or one. Inother words, in the light emitting device 1, the submount 30 or each ofthe submounts 30 is bonded to at least one semiconductor laser element20.

The electronic member 40 can be a MEMS. The electronic member 40 isdisposed on the bottom face of the base 10. Accordingly, it can be saidthat the electronic member is arranged on the bottom part 11 of the base10. The electronic member 40 is oriented such that the light emitted bythe semiconductor laser elements 20 irradiates the light-irradiated face41. Furthermore, the entire main portion of the light emitted by each ofthe three semiconductor laser elements 20 irradiates thelight-irradiated face 41.

The light-irradiated face 41 upwardly reflects the laterally emittedlight from the semiconductor laser elements 20. Accordingly, thelight-irradiated face 41 is inclined relative to the emission faces andthe optical axes. The light-irradiated face 41 is inclined at an angleof 10 to 80 degrees relative to the bottom face of the base 10.

The electronic member 40 is joined to the oblique face 51 of the supportmember 50. The support member 50 is positioned such that the obliqueface 51 faces in the direction toward the semiconductor laser elements20. Accordingly, it can be said that the electronic member 40 isdisposed on the oblique face 51. Arranging the electronic member 40 viathe support member 50 can simplify the shape of the electronic member40. The support member 50 is preferably formed of a material more easilyformable than the electronic member 40.

The lower face of the support member 50 is joined to the bottom face ofthe base 10. Accordingly, it can be said that the support member isdisposed on the bottom part 11 of the base 10. Joining the lower face ofthe support member 50 to the bottom face of the base 10 allows theoblique face 51 to incline relative to the bottom face.

The optical member 60 is disposed between the emission faces of thesemiconductor laser elements 20 and the light-irradiated face 41 of theelectronic member 40 in the top view. Furthermore, the optical member 60is disposed to allow the lens face 61 to face in a direction toward thelight-irradiated face 41. The three lenses individually correspond tothe light emitted from the three semiconductor laser elements 20. Thelenses respectively collimates the light from the semiconductor laserelements 20. Accordingly, the collimated light irradiates the MEMSemployed as the electronic member 40.

The MEMS reflects the irradiated light upwards. The main portions of thelight from the semiconductor laser elements 20 emitted towards theelectronic member 40 in a predetermined direction advance in a differentdirection from this. The MEMS reflects only the necessary portion of theirradiated light.

The light emitted by the semiconductor laser elements 20 diverges and iscollimated by the optical member 60 before hitting the electronic member40. Accordingly, the light-irradiated face 41 needs to extend higherthan the emission points of the semiconductor laser elements 20.Accordingly, the height of the electronic member 40 is higher than theheights of the semiconductor laser elements 20.

The light-irradiated face 41 is longer at the central portion in thedirection perpendicular to the bottom face of the base 10 and becomesshorter as the distance from the center increases. Accordingly, amongthe three semiconductor laser elements 20, one having the largestvertical divergence angle in the direction perpendicular to the bottomface is positioned in the center. This can effectively utilize thelight-irradiated face 41. However, the arrangement of the semiconductorlaser elements 20 is not limited to this.

In the light emitting device 1 illustrated in the drawings, the wirebonding locations for the electronic member 40 are higher than the wirebonding locations for the semiconductor laser elements 20. The lightemitting device 1 shown in the drawings can improve wire bondingconvenience by using the lower first stepped portion 13 for wire bondingthe semiconductor laser elements 20, and the higher second steppedportion 15 for wire bonding the electronic member 40 positioned higherthan the semiconductor laser elements 20.

In the state in which the submount 30 is disposed on the bottom face ofthe base 10, the height of the bonding face of the submount 30 forbonding the semiconductor laser elements 20 from the bottom face of thebase 10 is preferably the same as, or lower than, the height of thefirst stepped portion 13 of the base 10. The heights of the upper facesof the semiconductor laser elements 20 from the bottom face of the base10 preferably exceed or are higher than the height of the first steppedportion 13 of the base 10. This can facilitate connection with the firstwires 71.

In the state in which the electronic member 40 is disposed on the bottomface of the base 10, the height of the electronic member 40 exceeds theheight of the first stepped portion 13. The heights of the bondinglocations for the second wires 72 in the electronic member 40 exceed theheight of the first stepped portion 13. Furthermore, the bondinglocations of the second wires 72 for the electronic member 40 are higherpositioned than the upper edges of the main portions of the lightirradiated on the light-irradiated face 41.

The maximum height (the height of the upper edge) of thelight-irradiated face 41 of the electronic member 40 exceeds the heightof the first stepped portion 13 and the heights of the semiconductorlaser elements 20. The minimum height (the height of the lower edge) ofthe light-irradiated face 41 is smaller than the height of the firststepped portion 13 and the heights of the semiconductor laser elements20.

In the state in which the semiconductor laser elements 20 and theelectronic member 40 are disposed on the base 10, the inner lateralfaces of the base 10 can be divided into two opposing planar regionsbetween which the semiconductor laser elements 20 and the electronicmember 40 are interposed in series, and two opposing planar regionsbetween which the semiconductor laser elements 20 and electronic member40 are interposed in parallel. In the case in which the recessed portionhas a rectangular periphery in the top view as in the case of the lightemitting device 1, the inner lateral faces corresponding to the foursides of the rectangle constitute the planar regions.

The inner lateral faces of the first stepped portion 13 can be formed inthe two opposing planar regions between which the semiconductor laserelements 20 and the electronic member 40 are interposed in parallel.This can facilitate the positioning of the first wiring regions 14 whileavoiding the optical paths of the main portions of the light.

The inner lateral face of the second stepped portion 15 can be formed ina first of the two opposing planar regions between which thesemiconductor laser elements 20 and the electronic member 40 areinterposed in series, the first of the two opposing planar region beinglocated at a shorter distance from the electronic member 40 than fromthe semiconductor laser elements 20. Positioning the second steppedportion 15 in the rear of the light-irradiated face 41 of the electronicmember 40 can more effectively prevent the stepped portion fromintruding the optical paths of the light reflected by the electronicmember 40.

Furthermore the inner lateral face of the first stepped portion 13 canbe formed in a second of the two opposing planar regions between whichthe semiconductor laser elements 20 and the electronic member 40 areinterposed in series, the second of the two opposing planar regionsbeing located at a greater distance from the electronic member 40 thanfrom the semiconductor laser elements 20. This can provide the firstwiring regions 14 in the region extending in the opposite direction tothe direction of travel of the light from the emission faces of thesemiconductor laser elements 20, thereby facilitating the bonding of thewires 70 while avoiding the optical paths of the main portions of thelight.

In the light emitting device 1 illustrated in FIG. 3, the first steppedportion 13 has two opposing inner lateral faces between which thesemiconductor laser elements 20 and the electronic member 40 areinterposed in parallel, and one inner lateral face in the second of thetwo opposing planar regions between which the semiconductor laserelements 20 and the electronic member 40 are interposed in series, thesecond of the two planar regions being located at a greater distancefrom the electronic member 40 than from the semiconductor laser elements20. The second stepped portion 15 has one inner lateral face in thefirst of the two opposing planar regions between which the semiconductorlaser elements 20 and the electronic member 40 are interposed in series,the first of the two planar regions being located at a shorter distanceto the electronic member 40 than to the semiconductor laser elements 20.

The bonding portion at one end of each first wire 71 is bonded to afirst wiring region 14, and the other bonding portion is bonded to theupper face of a semiconductor laser element 20 or the upper face of thesubmount 30. A bonding region for bonding with a first wire 71 isprovided on the upper face of a semiconductor laser element 20 or theupper face of the submount 30.

It is not essential to connect all of the first wires 71 (i.e., allwires used to electrically connect the three semiconductor laserelements 20) to the first wiring regions 14. The bonding portion(s) ofone or plural first wires 71 at one end are connected to the firstwiring region(s) 14.

The bonding portion at one end of a second wire 72 is connected to asecond wiring region 16. The bonding portion at the other end isconnected to the electronic member 40. The electronic member 40 has abonding region for connection with a second wire 72.

It is not essential to connect all of the second wires 72 (i.e., allwires used to electrically connect the electronic member 40) to thesecond wiring regions 16. The bonding portion(s) of one or plural secondwires 72 at one end are connected to the second wiring region(s) 16.

The bonding region of the electronic member 40 is located higher thanthe center of the light-irradiated face 41. The height of the bondingregion of the electronic member 40 is higher than the bonding regions ofthe semiconductor laser elements 20 and the submount 30. The bondingregion of the electronic member 40 is preferably located in the vicinityof the upper edge of the surface where the light-irradiated face 41 isprovided. Providing the bonding region in such a location can facilitatethe bonding of the second wires 72.

The bonding region for the electronic member 40 with the second wires 72is preferably positioned at a distance from the light-irradiated face41. Providing the bonding region outside of the light-irradiated face 41can facilitate the installation of the second wires 72 without blockingthe light from the semiconductor laser elements 20.

In the light emitting device 1 illustrated in the drawings, the numberof wires to electrically connect the semiconductor laser elements 20 islarger than the number of wires to electrically connect the electronicmember 40. Because there are more first wires 71 than second wires 72,the number of first wiring regions 14 is larger than the number of thesecond wiring regions 16.

In the light emitting device 1 illustrated in the drawings, furthermore,the total length of the portions along the first stepped portion 13 islarger than the length of the portion along the second stepped portion15. A longer stepped portion provided for disposing a larger number ofwiring regions can improve a wire bonding convenience. Accordingly, themagnitude relation between the numbers of the first and second wiringregions is consistent with the magnitude relation between the lengthsalong the first stepped portion 13 and the second stepped portion 15.

The cover member 80 is disposed on the upper face of the base 10. Itthus can be said that the cover member is disposed on the lateral part12 of the base 10. The cover member 80 is bonded to the upper face ofthe base 10 positioned higher than the second stepped portion 15. Thecover member 80 when joined to the base 10 creates a closed spaceenclosed by the base 10 and the cover member 80. This space is where thesemiconductor laser elements 20 are arranged.

Furthermore, joining the cover member 80 to the base 10 underpredetermined atmospheric conditions can create a hermetically sealedspace. Creating a hermetically sealed space for arranging thesemiconductor laser elements 20 can reduce quality degradationattributable to dust.

In the light emitting device 1, the MEMS used as the electronic member40 can control the light exiting the light emitting device 1 through thecover member 80. The cover member 80 has light transmissivity for thelight emitted from the semiconductor laser elements 80. The opticalcontrol unit can be realized by electrically connecting the electronicmember 40 and a control mechanism provided outside of the light emittingdevice 1 via a wiring region of the base 10.

As disclosed above, in the light emitting device 1, because the bondingpositions for the semiconductor laser elements 20 and the bondingpositions for the electronic member 40 for electrical connection havedifferent heights, the connection of the wires 70 is facilitated byforming the stepped portions which have different heights in the base10. This can facilitate wire bonding.

Based on such a technical idea, a light emitting device according to thepresent invention is not limited to the first embodiment. In the lightemitting device 1, the first wires 71 for electrically connecting thesemiconductor laser elements 20 are bonded to the first stepped portion13 which is the lower positioned stepped portion, and the second wires72 for electrically connecting the electronic member 40 are bonded tothe second stepped portion 15 which is the higher positioned steppedportion. This is because the bonding positions for the electronic member40 are higher than the bonding positions for the semiconductor laserelements 20. However, if the bonding positions for the semiconductorlaser elements 20 are higher than the bonding positions for theelectronic member 40, the first wires 71 can preferably be bonded to thesecond stepped portion 15 and the second wires 72 to the first steppedportion 13.

In other words, one end of a first wire 71 is bonded to either a firstwiring region 14 or second wiring region 16, and one end of a secondwire 72 is bonded to the other of the first wiring region 14 and thesecond wiring region 16. Furthermore, the other end of the wire betweenthe first wire 71 and the second wire 72, the end bonded to the firstwiring region 14 is bonded at a lower position from the bottom face ofthe base 10 than the other end of the wire bonded to the second wiringregion 16. Furthermore, the other end of the wire between the first wire71 and the second wire 72, the other end bonded to the second wiringregion 16 is positioned higher from the bottom face of the base 10 thanthe first wiring region 14.

Second Embodiment

A light emitting device 2 according to a second embodiment will beexplained. FIG. 5 to FIG. 9 are drawings explaining an exemplaryembodiment of the light emitting device 2. FIG. 5 is a perspective viewof the light emitting device 2. FIG. 6 is a perspective view of thelight emitting device 2 in the state where the cover member 80 isremoved. FIG. 7 is a top view in the same state as in FIG. 6. FIG. 8 isa cross-sectional view taken along line VIII-VIII in FIG. 7. FIG. 9 is atop view when the electronic member 40 according to the secondembodiment is viewed from the light-irradiated face. The ellipses inFIG. 9 indicate the regions irradiated by the main portions of the lightfrom the semiconductor laser elements 20. The broken lines indicate themajor diameters of the ellipses.

The light emitting device 2 includes, as constituent elements, a base10, three semiconductor laser elements 20, a submount 30, an electronicmember 40, a support member 50, wires 70, and a cover member 80. Thelight emitting device 2 according to the second embodiment differs fromthe light emitting device 1 according to the first embodiment by nothaving an optical member 60. Furthermore, it differs from the lightemitting device 1 according to the first embodiment such that theelectronic member is a PD.

The light emitting device 2 illustrated in the drawings has the largernumber of first wires 71 than the light emitting device 1 shown in FIG.3. In the light emitting device 2 according to the second embodiment,the three semiconductor laser elements 20 are individually electricallyconnected such that the outputs can be individually adjusted. Eachsemiconductor laser element 20 is a multi-emitter having two emitters.

In the light emitting device 2, light receiving regions 242 eachcorresponding to the light emitted by the three semiconductor laserelements 20 are provided in the light-irradiated face 241 of theelectronic member 40. A portion of the light irradiated at each lightreceiving region 242 is received while the remaining portion isreflected upwards. It is preferable to reflect at least 90% of the lightin order to allow the device to output a large amount of light. In thecase of the light emitting device 2, three light receiving regions 242are arranged in a row in the same direction in which the threesemiconductor laser elements 20 are arranged in a row.

One light receiving region 242 corresponds to one semiconductor laserelement 20, and the light receiving regions 242 are separated. In otherwords, the light receiving regions 242 are spaced, not overlapping. Abonding region for a second wire 72 for electrical connection isprovided in each light receiving region 242.

As shown in FIG. 9, the electronic member 40 has, as the bonding regionsfor the second wires 72, first bonding regions 243 provided for eachlight receiving region, and one second bonding region 244 shared by themultiple light receiving regions.

All of the first bonding regions 243 and the second bonding region 244are provided above the regions to which the main portions of the lightfrom the semiconductor laser elements 20 irradiate. In other words, inthe light emitting device 2, the bonding regions are disposed in thepositions more distant than the regions irradiated by the main portionsof the light from the semiconductor laser elements 20.

In the top view, each light receiving region 242 has a laterally smallerwidth portion at the upper edge. Specifically, each light receivingregion has a shape that has a notched corner at the upper edge. Theshape and the position of the laterally narrower width portion areconsistent among the light receiving regions 242.

The first bonding regions 243 are disposed in the areas made availableby the reduced width portions of the light receiving regions. A firstbonding region 243 of a light receiving region 242 laterally projectsfrom the light receiving region 242. In the case in which another lightreceiving region 242 is provided adjacent thereto in the projectingdirection, the projected portion is disposed in the area made availableby the reduced width portion of the adjacent light receiving region 242.

The first bonding regions 243 are not provided on the straight linesextending along the major axes of the main potions of the lightirradiating the light receiving regions 242. In other words, the firstbonding regions 243 are provided in the locations that avoid thesestraight lines. As shown in FIG. 7 and FIG. 8, the second wires 72bonded to the first bonding regions 243 extend upwards therefrom andthen bonded to the second wiring regions 16. Avoiding the straight linesextending along the major diameters of the beams can inhibit the secondwires 72 from blocking the light reflected by the electronic member 40.

A first bonding region 243 arranged between two light receiving regions242 is provided between the straight lines extending along the majoraxes of the major portions of light irradiating the two light receivingregions 242. In other words, the first bonding region 243 does notbeyond the two straight lines. This can allow the second wire 72 toreadily avoid blocking the light reflected by an adjacent lightreceiving region 242.

Furthermore, a first bonding region 243 projects from one of twoopposing adjacent and closest sides of two adjacent light receivingregions 242, and the straight line extending along the other side goesthrough the first bonding region 243. Such a layout can provide thefirst bonding regions 243 such that the light receiving regions 242 arein close proximity to one another, thereby contributing to a reductionin the size of the light emitting device 2.

Moreover, in the top view, the second bonding region 244 is disposed inthe vicinity of the upper edge and on one of the sides of the electronicmember 40 opposite the projecting direction of the first bonding regions243. The second bonding region 244 is not disposed on the straight lineextending along the major axis of the major portion of the beamirradiating the light receiving region 242 closest to the second bondingregion 244.

The structure is not limited to one in which each semiconductor laserelement 20 corresponds to a light receiving region, i.e., one lightreceiving region can be provided to receive the lights from multiplesemiconductor laser elements 20. A single or plural light receivingregions can be provided in the light-irradiated face 241.

In the light emitting device 2, the PD employed as the electronic par 40can receive a predetermined percentage of the light irradiating thelight-irradiated face 241. The optical control unit can calculate theamount of light output by the light emitting device 2 and the amount oflight reflected by the electronic member 40 based on the amount of lightreceived. Based on the calculation results, various controls can beperformed such as an adjustment of the intensity of light emitted by thesemiconductor laser elements 20.

Third Embodiment

FIG. 10 is a perspective view of a light emitting device 3 according toa third embodiment. FIG. 11 is a top view of the light emitting device 3shown in FIG. 10 in the state where the cover member 80 is removed.

The light emitting device 3 includes, as constituent elements, a base310, three semiconductor laser elements 20, a submount 30, an electronicmember 40, a support member 50, wires 70, and a cover member 80. Ascompared to the base 10 according to the first and second embodiments,positions of the stepped portions are different in the light emittingdevice 3 according to the third embodiment. Furthermore, as compared tothe light emitting devices 1 and 2, the light emitting device 3 has afewer number of first wiring regions 14 that need to be secured.

The number of the first wiring regions 14 to be secured is affected by,for example, the number of semiconductor laser elements 20. In the caseof making the semiconductor laser elements 20 independently operable,the number of necessary wiring regions increases as the number ofsemiconductor laser elements 20 increases. Assuming that the wiringregions are provided in the first stepped portion described above, thenumber of first wiring regions 14 would increase.

For example, the number of the first wiring regions 14 to be secured canalso be affected by the number of emitters each semiconductor laserelement 20 has. In the case of making the emitters of the semiconductorlaser elements 20 independently operable, the number of necessary wiringregions increases as the number of emitters increases. Assuming thatsuch wiring regions are provided in the first stepped portion, thenumber of the first wiring regions 14 would increase.

In the light emitting device 3 illustrated in the drawings, each of thethree semiconductor laser elements 20 has a single emitter. The numberof the first wiring regions can vary depending on not only this, but onother factors. For example, there are instances where protective devicessuch as Zener diodes are provided to protect the semiconductor laserelements 20.

Depending on the number of necessary first wiring regions, the area tobe secured as the first stepped portion changes. Reducing the size ofthe base by appropriately designing the area where the first steppedportion is formed can lead to size reduction of the light emittingdevice.

In the lateral part 312 of the light emitting device 3, no inner lateralface of the first stepped portion 313 is provided in the first of thetwo opposing planar regions between which the semiconductor laserelements 20 and electronic member 40 are interposed in series, the firstof the two opposing planar regions having a smaller distance from theelectronic member 40 than from the semiconductor laser elements 20. Thiscan allow for a design of a small light emitting device.

In the light emitting device 3 illustrated in the drawings, the firststepped portion 313 has two opposing inner lateral faces between whichthe semiconductor laser elements and the electronic member areinterposed in parallel. No stepped portion defining an inner lateralface is provided in the second of the two opposing planar regionsbetween which the semiconductor laser elements 20 and electronic member40 are interposed in series, the second of the two opposing planarregions having a larger distance from the electronic member 40 than fromthe semiconductor laser elements 20.

In the light emitting device 3, the first stepped portion 313 is formedin the regions that do not intersect any straight line perpendicular tothe emission faces of the semiconductor laser elements 20 while passingthrough the three semiconductor laser elements 20 in the top view.

Light emitting devices according to certain embodiments have beendescribed above, but light emitting devices according to the presentinvention are not strictly limited to those described above. In otherwords, the present invention can be achieved without being limited tothe external shapes and structures of the light emitting devicesdisclosed by the embodiments. Furthermore, the present invention isapplicable to a device without making it essential to necessarilyinclude all of the constituent elements of the described embodiments.For example, in the event that a certain component of a light emittingdevice included in any of the embodiments is not recited in the claims,the claimed invention can still be applicable in view of the designflexibility of a person of ordinary skill in the art for such acomponent through the use of an alternative, an omission, a change inshapes or materials employed, or the like.

The light emitting devices disclosed with reference to the embodimentsdescribed above can be used in head-mounted displays, projectors,automotive headlights, lighting fixtures, displays, and the like.

What is claimed is:
 1. A light emitting device comprising: a base havinga bottom face and a lateral part surrounding the bottom face andextending upwards from the bottom face, wherein the lateral partcomprises a first stepped portion and a second stepped portion that areeach defined by an inner lateral face and an upper face, and wherein aheight of the second stepped portion from the bottom face is greaterthan a height of the first stepped portion from the bottom face; a lightemitting element disposed on the bottom face; an electronic memberdisposed on the bottom face and configured to be irradiated by lightemitted from the light emitting element; a first wiring region locatedon the first stepped portion; a second wiring region located on thesecond stepped portion; a plurality of wires connected to the lightemitting element and the electronic member, the plurality of wiresincluding: a first wire having a first end that is connected to thefirst wiring region, and a second end, and a second wire having a firstend that is connected to the second wiring region, and a second end;wherein a position of the second end of the first wire relative to thebottom face, is lower than a position of the second end of the secondwire relative to the bottom face.
 2. The light emitting device accordingto claim 1, wherein the light emitting element and the electronic memberare connected to the first and second wires.
 3. The light emittingdevice according to claim 2, wherein the second end of the first wire isconnected to the light emitting element, and the second end of thesecond wire is connected to the electronic member.
 4. The light emittingdevice according to claim 1, wherein: the inner lateral face of thefirst stepped portion meets the bottom face; and the inner lateral faceof the second stepped portion meets the bottom face.
 5. The lightemitting device according to claim 1, wherein: a length of a portionwhere the inner lateral face of the second stepped portion meets thebottom face is larger than a length of a portion where the inner lateralface of the second stepped portion meets the upper face of the firststepped portion.
 6. The light emitting device according to claim 1,wherein: the base comprises a bottom part having the bottom face; andthe lateral part and the bottom part are monolithic.
 7. The lightemitting device according to claim 1, wherein: the base comprises abottom part having the bottom face; and a thermal conductivity of thebottom part is higher than a thermal conductivity of the lateral part.8. The light emitting device according to claim 1, wherein: theelectronic member is configured to be irradiated by an entire mainportion of the light emitted from the light emitting element.
 9. Thelight emitting device according to claim 8, wherein: the electronicmember is configured to allow at least 80% of the main portion of thelight radiating in a predetermined direction from the light emittingelement to radiate in a direction different from the predetermineddirection.
 10. The light emitting device according to claim 1, wherein:the electronic member comprises a microelectromechanical system or aphotodiode.
 11. The light emitting device according to claim 1, wherein:the electronic member is configured such that a face of the electronicmember on which the light emitted from the light emitting elementirradiates is inclined at an angle of 10 to 80 degrees relative to thebottom face.
 12. The light emitting device according to claim 3, furthercomprising: a submount on which the light emitting element is arranged;wherein the second end of the first wire is bonded to an upper face ofthe light emitting element or an upper face of the submount.
 13. Thelight emitting device according to claim 1, wherein: an inner lateralface of the second stepped portion is formed in a first of two opposingplanar regions between which the light emitting element and theelectronic member are interposed in series, the first of the planarregions having a shorter distance from the electronic member than fromthe light emitting element.
 14. The light emitting device according toclaim 13, wherein: inner lateral faces of the first stepped portion areformed in two opposing planar regions between which the light emittingelement and the electronic member are interposed in parallel.
 15. Thelight emitting device according to claim 14, wherein: no inner lateralface of the first stepped portion is formed in the first of the twoopposing planar regions between which the light emitting element and theelectronic member are interposed in series.
 16. The light emittingdevice according to claim 15, wherein: an inner lateral face of thefirst stepped portion is formed in a second of the two planar opposingregions between which the light emitting element and the electronicmember are interposed in series, the second of the two planar regionshaving a longer distance from the electronic member than from the lightemitting element.
 17. The light emitting device according to claim 1,further comprising: a support member disposed on the bottom face of thebase and having an oblique face oblique to the bottom face, wherein theelectronic member is disposed on the oblique face of the support member.18. The light emitting device according to claim 1, further comprising:a cover member bonded to the upper face of the base at a position higherthan the second stepped portion, and hermetically sealing a space inwhich the light emitting element is disposed.